Energy Supply Mix (Renewables & Fossil Fuels)

Types of Energy Sources

Energy sources are broadly divided into two categories: renewable and fossil fuels.

Renewable Energy Sources

• Wind power: Energy generated by wind turbines converting kinetic energy into electricity.
• Solar power: Energy from sunlight captured by solar panels and converted into electricity or heat.
• Hydroelectric power: Energy from flowing water, usually from dams, turning turbines to generate electricity.
• Biomass: Organic material (like wood, crops, or waste) burned or converted to produce energy. Biomass can be renewable if sourced sustainably, but may contribute to emissions if not managed properly.
• Geothermal energy: Heat energy from beneath the Earth's surface used for heating or electricity generation.

Fossil Fuel Energy Sources

• Coal: A solid fossil fuel formed from ancient plant remains, burned to produce heat and electricity.
• Oil (petroleum): A liquid fossil fuel used for heating, electricity, and transport fuels like petrol and diesel.
• Natural gas: A gaseous fossil fuel used for heating, electricity generation, and cooking.

Differences in Origin and Renewability

Renewable energy sources come from natural processes that are constantly replenished, such as sunlight, wind, and water flow. They are considered sustainable because they do not run out on a human timescale.

Fossil fuels form over millions of years from the remains of plants and animals buried under sediment. They are finite resources, meaning they will eventually run out as they are extracted and used faster than they form.

Current Energy Supply Mix in the UK

The UK’s energy supply mix has changed significantly over recent decades, shifting from heavy reliance on fossil fuels towards more renewable sources.

Proportion of Renewables: As of 2020, renewables contribute around 40% of the UK’s electricity generation. This includes wind, solar, hydro, and biomass.

Proportion of Fossil Fuels: Fossil fuels (coal, oil, natural gas) still provide a significant share but have declined sharply. Coal use has dropped from about 40% in 2012 to less than 5% today, while natural gas remains an important source, providing roughly 35-40% of electricity.

The UK government aims to increase renewable energy’s share further to meet climate targets and reduce carbon emissions.

Trends show:

• A rapid decline in coal use due to environmental concerns and government policies.
• Growth in wind power, especially offshore wind farms in the North Sea.
• Expansion of solar power, particularly in southern England.
• Continued use of natural gas as a flexible backup to renewables.

For instance, in 2020, renewables generated more electricity than fossil fuels for the first time in the UK.

Advantages of Renewable Energy Sources

Sustainability: Renewable energy sources are sustainable because they rely on natural processes that will not run out, such as sunlight and wind. This means they can provide energy indefinitely without depletion.

Low Emissions: Renewables produce little or no greenhouse gases during operation, helping to reduce air pollution and combat climate change. For example, wind turbines and solar panels generate electricity without releasing carbon dioxide.

Energy Security: Using renewables reduces dependence on imported fossil fuels, which can be affected by political instability or price fluctuations. The UK’s own wind and solar resources help provide a more secure and stable energy supply.

For example, offshore wind farms in the North Sea harness strong, consistent winds close to the UK, reducing reliance on foreign energy.

Disadvantages of Fossil Fuels

Environmental Pollution: Burning fossil fuels releases pollutants such as sulphur dioxide, nitrogen oxides, carbon monoxide, and particulate matter, which cause acid rain, harm ecosystems, and affect human health.

Finite Resources: Fossil fuels are non-renewable and will eventually run out. As reserves become harder to access, extraction becomes more expensive and environmentally damaging.

Contribution to Climate Change: Fossil fuel combustion releases large amounts of carbon dioxide, a greenhouse gas that traps heat in the atmosphere. This is the main driver of global warming and climate change.

For example, coal-fired power stations are among the largest sources of carbon emissions in the UK, although their use has declined.